Combustion engines are often used for power generation applications. These engines can be gaseous-fuel driven and implement lean burn, during which air/fuel ratios are higher than in conventional engines. For example, these gas engines can admit about 75% more air than is theoretically needed for stoichiometric combustion. Lean-burn engines increase fuel efficiency because they utilize homogeneous mixing to burn less fuel than a conventional engine and produce the same power output.
One shortcoming of heavy duty natural gas engines is that they may not be able to operate using a wide range of fuel variants such as, for example, fuels having a wide range of varying methane numbers. Engine parameters such as, for example, compression ratio may limit the range of fuel that heavy duty natural gas engines may use, thereby limiting the applications for which a given engine may be used.
A natural gas engine system is described in European patent application publication EP 0 945 606 A2 (the '606 publication), by Kawamura. The '606 publication discloses an engine system having a turbocharger, and valve controllers for varying a timing of intake valves of an engine cylinder, to vary an effective compression ratio. The '606 publication also discloses temperature sensors for sensing a temperature of the intake air and combustion chamber walls. A controller unit controls the valve controllers based on input from the temperature sensors.
Although the engine system of the '606 publication may vary intake valve timing based on a sensed temperature, it fails to adjust engine operation based on fuel composition. Therefore, the engine system of the '606 publication may fail to increase the range of fuel variants that can be used in the engine.
The present disclosure is directed to overcoming one or more of the shortcomings set forth above and/or other deficiencies in existing technology.